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Protective effect of phyllanthus niruri on dmba croton oil mediated carcinogenic response and oxidative damage in accordance to histopathological studies in skin of mice
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Protective effect of phyllanthus niruri on dmba croton oil mediated carcinogenic response and oxidative damage in accordance to histopathological studies in skin of mice

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  • 1. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.1, No.4, 2011 Protective Effect of Phyllanthus niruri on DMBA/Croton Oil Mediated Carcinogenic Response and Oxidative Damage in Accordance to Histopathological Studies in Skin of Mice Priyanka Sharma, Jyoti Parmar, Preeti Verma, Priyanka Sharma, P.K.Goyal*Radiation & Cancer Biology Laboratory, Department of Zoology, University of Rajasthan, Jaipur-302 004, India * E-mail of the corresponding author: pkgoyal2002@gmail.comAbstractThe current study has been designed to unveil the preventive effect of Phyllanthus niruri extract (PNE) ontwo stage skin carcinogenesis and oxidative damage in Swiss albino mice. Single topical application of 7,12-dimethylbenz (a) anthracene (DMBA), followed by croton oil thrice weekly produced 100% incidenceof tumors in carcinogen control animals (Gr. III) by 16 weeks. On the other hand, oral administration ofanimals with PNE (1 week before of DMBA application & continued until the end of experiment, Gr. IV),significantly reduced the tumor incidence, tumor burden, tumor volume and weight and the number oftumors but prolong the latent period of tumor occurrence, as compared with carcinogen control animals.Furthermore, administration of PNE protected against the losses provoked in levels of glutathione, Vit.C,total proteins and activity of catalase and superoxide dismutase in skin and liver of animals by theapplication of DMBA/croton oil, concomitantly, the levels of lipid peroxidation were also reducedsignificantly. P. niruri administration profoundly reverted back the pathological changes observed in skinand liver of cancerous animals. From the results, P. niruri extract proves to scavenge free radical and foundto be a potent chemopreventive agent against chemical induced skin carcinogenesis.Keywords: carcinogenesis, Phyllanthus niruri, cancer chemoprevention, tumor incidence, reactive oxygenspecies (ROS), antioxidant enzymes1. IntroductionAn increasingly important health problem in the world is the rising incidence of genetic diseases thatinclude age related neurodegenerative diseases, cardiovascular diseases and cancer. Ironically, this is partlydue to the increasing longevity of the population, which results from better living and working conditions(Migliore and Coppede` 2002). Even if the etiology of these diseases is not completely understood, but forthe sake of improved human health and the quality of life, it will be essential to obtain a betterunderstanding of the key biochemical mechanisms and risk factors for such chronic diseases. Free radicalsare found to be involved in both initiation and promotion of multistage carcinogenesis. These highlyreactive compounds can act as initiators and/or promoters, cause DNA damage, activate procarcinogens,and alter the cellular antioxidant defense system. Antioxidants, the free radicals scavengers, however, areshown to be anticarcinogens. They function as the inhibitors at both initiation andpromotion/transformation stage of carcinogenesis and protect cells against oxidative damage. (Yin sun1990).The attractiveness of naturally occurring compounds for cancer chemoprevention has escalated in recentyears. An ideal chemopreventive/therapeutic agent would restore normal growth control to preneoplastic orcancerous cells by modulating aberrant signaling pathways and/or inducing apoptosis. It should target themultiple biochemical and physiological pathways involved in tumor development, while minimizingtoxicity in normal tissues (Manson et al. 2005; Mukhtar and Ahmad 1999a; Mukhtar and Ahmad 1999b;Yance and Sagar 2006). 16
  • 2. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.1, No.4, 2011Among the human diseases treated with medicinal plants cancer is one of the most important geneticdisease. Every year, millions of people are diagnosed with cancer, leading to death in a majority of thecases. According to the American Cancer Society (American Cancer Society 2006), deaths arising fromcancer constitute 2–3% of the annual deaths recorded worldwide. A large number of chemotherapeuticagents used in cancer treatment have been discovered from natural products. Similarly, several laboratoriesthroughout the world have directed considerable efforts towards discovering new chemopreventive agentsfrom natural products because of their wide biological activities, higher safety right kind of plant materialwhich is therapeutically margins and lesser costs. In this regard the genus Phyllanthus includes 500temperate and tropical species many of which are used medicinally in different countries. Phyllanthusniruri L., belonging to family Euphorbiaceae, is a common weed found in both cultivated fields andwastelands in India. It is an annual herb with height varying between 30 and 60 cm. Its roots, leaves, fruits,milky juice, and whole plants are used as medicine (Kirtikar and Basu 1935). Fruits are useful fortubercular ulcers, wounds, sores, scabies and ring worm (Agharkar 1991). The fresh root is believed to bean excellent remedy for jaundice, dropsy and genitourinary infections (Chopra et al. 1956). The infusion ofthe root and leaves is a good tonic and diuretic when taken cold in repeated doses (Ambasta 1986;Satyavati et al. 1987). In different parts of India, especially, in Chhattisgarh state, it is used as a richtraditional medicine (Caius 1986). P. niruri has shown clinical efficacy in viral Hepatitis B for which noeffective specific therapy is available (Paranjpe 2001). Fresh juice and powder of dried plant are used mostfrequently in Ayurvedic preparations (Sastry and Kavathekar 1990). P. niruri is still widely used in herbalmedicine in South America, remaining the most popular remedy for gallstones and kidney stonesthroughout the continent (Taylor 2003). In Peruvian herbal medicine, it is also used for hepatitis, urinaryinfections, and as a diuretic (Devi 1986). There are also reports of a host of other activities of different partsof P. niruri and its constituents (Taylor 2003; Bagalkotkar et al. 2006).Considering the myriads of phytochemicals and therapeutic potential in Phyllanthus niruri, the aim of thisinvestigation is to study and evaluate the preventive effect of the plant hydro-alcoholic extract onDMBA/croton oil mediated carcinogenic response and oxidative damage in mammals.2. Materials and Methods2.1 Animal care and HandlingThe animal care and handling was approved by our institution and was done according to guidelines set bythe World Health Organization (WHO), Geneva, Switzerland, and the Indian National Science Academy(INSA), New Delhi, India. The study was conducted on random-breed male Swiss albino mice (7-9 weeksold) weighing 24 ± 2 gm. These animals were housed in polypropylene cages in the animal house undercontrolled conditions of temperature (25°C ± 2°C) and light (14 light :10 dark). The animals were fed astandard mouse feed procured from Aashirwad Industries, Chandigarh (India), and water ad libitum. Fouranimals were housed in one polypropylene plastic cage containing saw dust (procured locally) as beddingmaterial. As a precaution against infections, tetracycline hydrochloride water was given to these animalsonce each fortnight.2.2 ChemicalsThe initiator, 7, 12-dimethylbenz[a]anthracene (DMBA) and the promoter croton oil were procured fromSigma Chemicals Co., St Louis, USA. DMBA was dissolved at a concentration of 100 µg/100 µl inacetone. Croton oil was mixed in acetone to give a solution of 1% dilution.2.3 Preparation of Phyllanthus niruri extract (PNE)The whole plant P. niruri was collected after proper identification (Voucher No. RUBL 20247) by acompetent botanist from the Herbarium, Department of Botany, University of Rajasthan, Jaipur. The wholeplant was powdered in a mixture and the hydro-alcoholic extract was prepared by refluxing with the doubledistilled water (DDW) and alcohol (3:1) in a round bottom flask for 36 (12x3) hrs. at 40ºC. The liquid 17
  • 3. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.1, No.4, 2011extract was filtered, cooled and concentrated by evaporating its liquid contents in oven and collected. Thepowdered extract, termed Phyllanthus niruri extract (PNE), was redissolved in DDW prior for the oraladministration in mice. The required dose for treatment was prepared by dissolving the extract in DDW at adose level of 500 mg/kg body weight.2.4 Experimental Design2.4.1 Determination of the effect of P.niruri on DMBA induced carcinogenesisGroup I: Vehicle treated control / Normal (n = 10) - Animals of this group received topical application ofacetone (100 µl/ mouse) on the shaven dorsal skin, and double distilled water (equivalent to PNE i.e.100 µl/ mouse) was given by oral gavage for 16 weeks.Group II: PNE treated control / Drug alone (n = 10) - Animals of this group were put on a normal diet andadministered Phyllanthus niruri extract at a dose of 250 mg/kg/b. wt. /day orally once in a day for 16 weeksstudy period.Group III: Carcinogen treated Control (n = 10) – These animals were treated with a single dose of DMBA(100 µg/100 µl of acetone) over the shaven area of the skin. Two weeks later, croton oil (1% in 100 µl ofacetone) was applied as a promoter 3 thrice a week until the end of the experiment (i.e. 16 weeks).Group IV: PNE treated Experimental (n = 10) – Animals of this group were administered P. niruri extract(250 mg/kg/b. wt./animal/day) by oral gavage starting from 7 days before of DMBA application andcontinued until the end of experiment (i.e. 16 weeks).The following parameters were taken into consideration:(i) Cumulative number of papillomas: The total number of papillomas appeared till the termination of theexperiment. (ii) Tumor incidence: The number of mice carrying at least one tumor, expressed as apercentage incidence (iii) Tumor yield: The average number of tumors per mouse (iv) Tumor burden: Theaverage number of tumors per tumor bearing mouse (v) Size of tumor & Weight; (vi) Body weight; (vii)Average latent period: The time lag between the application of the promoting agent and the appearance of50% of tumors was determined. The average latent period was calculated by multiplying the number oftumors appearing each week by the time in weeks after the application of the promoting agent and dividingthe sum by total number of tumors.Average latent period = ΣFX NWhere F is the number of tumors appearing each week, X is the numbers of weeks, and N is the totalnumber of tumors.2.4.2 Determination of the effect of P. niruri on enzyme analysis of liver and skinThe animals from all the groups were sacrificed by cervical dislocation 16th week after the commencementof treatments and their liver as well as dorsal skin affected by tumors were quickly excised and washedthoroughly with chilled 0.9% NaCl (pH 7.4). Both the tissues (liver & skin) were then weighed and blotteddry. A 10% tissue homogenate was prepared from the part of the sample in 0.15 M Tris-KCL (pH 7.4), andthe homogenate was then centrifuged at 2500 rpm for 10 minutes. The supernatant thus obtained was takenfor estimation of following biochemical parameters. The level of reduced GSH was estimated as an acidsoluble non-protein sulfhydryl group by the method of Moron et al. (1979). The level of lipid per oxidationwas estimated spectrophotometrically by thiobarbituric acid reactive substances (TBARS) method, asdescribed by Ohkhawa et al. (1979). Superoxide dismutase activity was assayed by the method ofMarklund and Marklund (1974) and the results were expressed as U/mg protein, where U is the unit ofenzyme activity defined as the amount of enzyme necessary for inhibiting the 50% auto oxidation ofpyrogallol. Auto-oxidation of pyrogallol in Tris-HCL buffer (50 mM, pH-7.5) was measured by the increasein absorbance at 420 nm.Catalase was assayed on a UV Spectrophotometer at 240 nm by monitoring the decomposition of H2O2, as 18
  • 4. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.1, No.4, 2011described by Aebi (1984). The activity of the enzyme was expressed as U/mg of tissue, where U is µ moleof H2O2 reduced/min/mg tissue. For the tissue ascorbic acid (Vit.C) determination, the fresh organs wereweighed, homogenized in acetate buffer (20mg/ ml) and extracted with cold 4 per cent trichloroacetic acid,centrifuged, and filtered. Ascorbic acid was determined by the method of Roe and Kuether and measured asmg/ml. Protein estimation was determined by the method of Lowry et al (1951) using bovine serumalbumin as a standard.2.4.3 Effect of P. niruri on histopathology of SkinSkin of all the animals were excised out and fixed in Bouin’s fixatives for 24-28 hr. and processed by theusual method of paraffin embedding. Sections of 5 µm thickness were taken through microtome, stainedwith hematoxylin & eosin and were evaluated for pathological changes using binocular light microscope.2.5 Statistical AnalysisThe results are expressed as the mean ± standard error. The data from biochemical determinations wereanalyzed using the Student’s t- test.3. Results3.1 Effect of P. niruri on papilloma formationTable 1 and 2 show the results of the protective effect of P. niruri on DMBA induced skin carcinogenesis.Animals of all groups did not show any significant variation in body weight during the entire experimentand there was no mortality. No noticeable signs of illness e.g. weight loss, diarrhea, alopecia were detectedin mice of PNE treated control (Gr. II) group. Similarly no papilloma has been observed in the vehicletreated control (Gr. I) as well as PNE treated control group (Gr. II) whereas the incidence of papilloma wasdifferent in DMBA-croton oil treated group (Gr. III 100 %) as compared with the DMBA-croton oil-PNEtreated group (Gr. IV 40 %). Cumulative number of papillomas was 62 in carcinogen treated control (Gr.III) which was significantly reduced to 15 in PNE treated experimental group. The tumor burden and yield(3.75 and 1.5 respectively) was considerably reduced in PNE treated experimental group as compared tocarcinogen treated control group (6.2). The average tumor weight of the carcinogen treated control was1.37 gm whereas it was only 0.38 gm for the PNE treated experimental group. The average latent periodwas observed as 10.66 in PNE treated experimental group which was found to be lesser (i.e.7.93) incarcinogen treated control Group.3.2 Effect of P. niruri on enzyme analysis of liver and skin3.2.1 Reduced glutathioneIn the levels of GSH 98.04 and 97.13% decrease (p ≤ 0.001) in liver and skin of animals of carcinogentreated control group (Gr. III), and a 55.12 and 42.38% decrease (p ≤ 0.001) were observed in both thetissues of animals treated with DMBA/croton oil/PNE as compared with vehicle treated control animals(Gr. I). There was an average 2192.30 and 1907.69% increase (p ≤ 0.001) in the GSH levels in liver andskin of animals treated with DMBA/croton oil/PNE in relation to both the tissues of carcinogen treatedcontrol animals. (Fig. 1)3.2.2 Lipid peroxidationThe level of LPO in liver and skin of animals treated with DMBA/croton oil (Gr.III) was increased by 390and 239.39 % (p ≤ 0.001), whereas animals treated with DMBA/croton oil/PNE (Gr. IV) exhibited only53.00 and 16.01% increase (p ≤ 0.001) with respect to vehicle treated control animals. In general, a 69.08and 65.81 % decrease in the level of LPO was observed in the liver and skin of animals treated withDMBA/croton oil/PNE (Gr. IV) in comparison with the LPO levels in both the tissues of DMBA/croton oiltreated animals. (Fig 2)3.2.3 Superoxide dismutase 19
  • 5. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.1, No.4, 2011In the activity of SOD a decrease of 35.36 and 37.04% (p ≤ 0.001) was observed in the liver and skin ofDMBA/croton oil treated animals (Gr. III), whereas animals treated with DMBA/croton oil/PNE exhibiteda 12.32 and 11.17% decrease (p ≤ 0.001) as compared with the animals of normal (Gr. I). There was anaverage 35.66 and 41.07% increase (p ≤ 0.001) in SOD in both the tissues of animals treated withDMBA/croton oil/PNE as compared with the level in DMBA/croton oil-treated animals. (Fig. 3)3.2.4 CatalaseAs compared with vehicle treated control animals (Gr. I), the activity of CAT in liver and skin ofcarcinogen treated control animals (Gr. III) exhibited a 83.79 and 78.93% decrease (p ≤ 0.001), whereas38.70 and 30.57 % decrease (p ≤ 0.001) was measured in P.niruri treated experimental group (Gr. IV). Ingeneral, there was nearly 278.15% and 229.61% increase (p ≤ 0.001), in the activity of CAT in the liverand skin of animals treated with DMBA/croton oil/PNE (Gr. IV) as compared with the activity in theDMBA/croton oil treated animals(Gr.III).(Fig. 4)3.2.5 Vitamin CAs compared with vehicle treated control animals (Gr. I), the activity of Vit.C exhibited a 30.54% and37.68% decrease (p ≤ 0.001) in liver and skin of carcinogen treated control animals (Gr. III), while suchdecrease was recorded as 7.88 and 10.05 % (p ≤ 0.001) in P.niruri treated experimental group (Gr. IV). Ingeneral, there was an 32.62 and 44.35% increase (p ≤ 0.001), in the activity of CAT in the liver and skin ofanimals treated with DMBA/croton oil/PNE (Gr. IV) as compared with the activity in the DMBA/croton oiltreated animals(Gr.III).(Fig. 5)3.2.6 ProteinTotal proteins level in liver and skin was found to be decreased to 77.04 and 67.26% (p ≤ 0.001) incarcinogen treated control group (Gr.III), and to 27.37 and 15.04 % (p ≤ 0.001) in PNE treatedexperimental group (Gr. IV) as compared with vehicle treated control animals (Gr. I). An average increase(p ≤ 0.001) of 216.44% and 159.51% in the total proteins level was noted in both the tissues of animals ofPNE treated experimental group IV in relation to the protein level of carcinogen treated group.( Fig. 6)3.3 Effect of P. niruri on histopathology of SkinThe histopathological examination of the skin of carcinogen control animals showed hyperkyratosis (i.e.the thickening of keratinized layer over the epidermis), epidermal hyperplasia, atypical nuclei (enlarged andhyperchromatic), interdermal proliferation, dermal invasion and keratin pearls throughout the epidermis.Some of the cells break through the basement membrane, the process has become invasive. This invasivetumor cells exhibit enlarged nuclei with angulated contours. All of these symptoms were found to beminimal in PNE treated group of animals (Gr. IV) (Fig. 7 A–E).4. DiscussionProduction of reactive oxygen species (ROS) and subsequently oxidative stress cause development ofcancer (Guyton and Kensler 1993). The involvement of free radicals in both the initiation as well as thepromotion stage, the biochemical events related in each stage and the metabolic alterations associated withcancer development (Boutwell 1974) have been highlighted with the help of two-stage skin carcinogenesis.Plants, vegetables, herbs, and spices used in folk and traditional medicine have been accepted currently asone of the main sources of cancer chemopreventive measures. Therefore, the present study has beendesigned to evaluate the preventive effect of the hydro-alcoholic extract of Phyllanthus niruri onDMBA/croton oil mediated carcinogenic response and oxidative damage. The results show a significantincrease in tumor latency by administration of PNE in DMBA initiated and croton oil promotedcarcinogenesis. This may be due to the delay in the promotion phase by PNE administration. Besides this, adecrease in tumor weight and size, significant reduction in tumor incidence, tumor burden and cumulativenumber of papillomas was observed in the group where PNE was given alongwith carcinogen treatment.Even in another study conducted in our laboratory, PNE increased tumor latency and decreased tumor 20
  • 6. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.1, No.4, 2011volume and efficiency of tumor conversion. (Sharma et al. 2009).Since the compounds exhibiting antioxidant and/or anti-inflammatory activities are expected to be effectiveanti-tumor promoting agents (Surh 2002), the present study confirms that the phytochemical fraction of P.niruri, containing lignans, phyllanthin, hypophylanthin, flavonoids, glycosides and tannin constituents(Murugaiyah et al. 2007 and Bagalkotkar et al. 2006) inhibit the formation of mouse skin tumors. Alaboratory study reported that Phyllanthus seems to have the ability to inhibit two of the pro-inflammatoryenzymes (COX-2 and iNOS), making it potentially useful in the fight against inflammatory diseases suchas cancer (Keimer et al. 2000). Previous studies compared the antidiabetic, hypolipidemic, and antioxidantproperties of Phyllanthus niruri in normal, insulin-dependent diabetes mellitus (IDDM), and non-insulin-dependent diabetes mellitus (NIDDM) animals through evaluating the effects on carbohydrate and lipidmetabolism and antioxidant activities. (Jasmin et al. 2007). Hepatoprotective activity of the phyllanthusextract was also demonstrated in vivo by the inhibition of the carbon tetrachloride (CCl4) – inducedformation of lipid peroxides in the liver of rats (Harish and Shivanandappa 2006). Data from these studiesand the present study suggest that the antioxidant activity of P. niruri is likely to be involved in thereduction of ROS induced by DMBA/croton oil thereby inhibiting tumor development.Histopathology of the skin and tumors observed at 16th weeks after DMBA/ croton oil treatment showedsevere hyperkyratosis (i.e. the thickening of keratinized layer over the epidermis), epidermal hyperplasia,atypical nuclei (enlarged and hyperchromatic), interdermal proliferation, dermal invasion and keratinpearls, suggesting invasive squamous cell carcinoma. On the other hand, intact basal cell layer anddysplastic lesions characterized benign papillomas were observed in DMBA/croton oil/PNE-treated animals(Gr. IV). This direct evidence shows that PNE application inhibits the carcinoma formation and conversionefficiency of papillomas into frank squamous cell carcinoma.Oxidative stress is associated with the peroxidation of cellular lipids which is determined by measurementof TBA-reactive substances. Lipid peroxidation is increased during the carcinogenic process andmalondialdehyde (MDA), a product of lipid peroxidation was observed to be mutagenic and carcinogenic(Apaja 1980 and Basu 1983). The concentration of lipid peroxidation products may reflect the degree ofoxidative stress in carcinogenesis. In the present study we evaluated TBA-reactive substances (MDA) todetermine the protective activity of PNE from oxidative damage in carcinogenesis. The level of TBAreactive substances in the liver and skin of mice was significantly decreased with PNE administration whencompared to the DMBA-induced tumor bearing carcinogen control mice. The decreased level of TBAreactive substances results that PNE can debilitate the pathological conditions of carcinogenesis byinhibition of lipid peroxidation. The phytoconstituents responsible for the inhibition of lipid peroxidationmay be due to the presence of flavonoids such as rutin, quercetin, queritrin, etc., present in the plant extract(Bagalkotkar et al. 2006).Antioxidants are the body’s first resource for protection against the diverse free radicals and other oxidativefactors (Cross et al. 1987). The antioxidant system comprises various functional components includingdifferent antioxidant enzymes, together with the substances that are capable of reducing ROS or preventingtheir formation. Among them, SOD and CAT enzymes are important scavengers of superoxide ion andhydrogen peroxide. These enzymes prevent generation of hydroxyl radical and protect the cellularconstituents from oxidative stress (Scott et al. 1991).The non-protein thiol GSH serves as a scavenger ofdifferent free radicals and is one of the major defenses against oxidative stress (Halliwell and Gutteridge1999). Vitamin-C is necessary for the recycling of gluthione and is an effective quencher of reactive oxygenspecies. The pronounced effect of Vitamin-C in decreasing the incidence and delaying the onset ofmalignant tumors has already been reported (Pauling 1991). The present study showed the significantreduction (p < 0.001) in the activities of antioxidant enzymes (SOD & CAT) and non-enzymatic antioxidantsystem (GSH & Vit.C) in DMBA treated carcinogen control group (Gr. III) as compared to the PNE treatedexperimental group (Gr. IV) that could be responsible for increased TBARS levels observed duringDMBA-induced oxidative damage. Our result is supported by findings reported previously for liver andskin of mice (Leemol and Kuttan 2001; Chaudhary et al. 2007).The data obtained in experiments provedthat the components of Phyllanthus niruri extract (PNE) might act as scavengers of reactive oxygenspecies, and hence could inhibit microsomal peroxidation, membrane destruction and enzyme damage 21
  • 7. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.1, No.4, 2011(Czinner et al. 2001).Several phytochemicals have been tested in two-stage skin carcinogenesis model, and found to havesubstantial potential to prevent cancer (Slaga 1984; Singh et al. 2002). Quercetin is one of such componentof P. niruri extract. Our results and other reports (Herzog et al. 2004; Hansen et al. 1997) suggest quercetinmight be one of the active compounds responsible for the anti-carcinogenetic and apoptosis-inductioneffects of P. niruri extract. Ellagic acid is active in antimutagenesis assay and has been shown to inhibitchemically induced cancer in the lung, liver, skin and esophagus of rodents and TPA-induced tumorpromotion in mouse skin (Stoner and Mukhtar 1995). Some lipids like ricinoleic acid, linoleic acid,dotriacontanoic acid etc. are components of PNE. These fatty acids may be responsible for the observedanticarcinogenic effects of the present study. Numata et al. (1994) reported that the glyceride fraction fromCoix seeds containing fatty acids i.e. palmitic, stearic, oleic and linoleic acid inhibit Yoshida sarcomagrowth in rats. They suggested that the glyceride components of Coix seeds may be metabolized tomonolinoleic acid in vivo and this inhibits tumorigenesis. In the present study, perhaps a similar mechanismmay be operating in the inhibition of skin carcinogenesis by the PNE.5. ConclusionThe anticarcinogenic and anti-oxidative activity of hydro-alcoholic extract of Phyllanthus niruri (PNE) asobserved in our study is due to its stimulatory effect on both enzymatic and non-enzymatic antioxidantsystems in the experimental mice. Consequently, the formation of tumors and oxidative damage induced byDMBA/croton oil in the skin of mice is suppressed with the administration of hydro-alcoholic extract ofPhyllanthus niruri (PNE) due to the reduction in the level of reactive oxygen species (ROS) as indicated bythe reduction in the level of TBARS and the induction of recovery and repair process in the liver and skinof mice. The mechanism of action of the extract seems to be (a) suppression of proliferation, (b)suppression of activation of carcinogen, and (c) anti-oxidant activity of the extract. The phytochemicalspresent in hydro-alcoholic extract of Phyllanthus niruri (PNE), responsible for these activities, may belignans phyllanthin and hypophyllanthin and other components as described above. (Khatoon et al., 2006).Further studies are needed to elaborate whether some other compounds present in Phyllanthus niruri arealso responsible for the protective effect against carcinogenesis and oxidative damage and the molecularbasis of their mode of action.6. Acknowledgements and FundingsPriyanka Sharma gratefully acknowledges for laboratory facilities to Center for Advanced Studies (CAS),Department of Zoology, University of Rajasthan, Jaipur (India). This research received no specific grantfrom any funding agency in the public, commercial, or not-for- profit sectors.ReferencesAebi, H. (1984), “Catalase: in vitro”, In: S.P.Colowick, N.O.Kaplan (eds), Method in Enzymology,Academic press, New York, 105, 121-126.Agharkar, S.P. (1991), “Medicinal Plants of Bombay Presidency”, Scientific Publ., Jodhpur, India, 120–122.Ambasta, S.P. (1986), “The Useful Plants of India”, Publications and Information Directorate, CSIR, NewDelhi, 329.American Cancer Society, A biotechnology company dedicated to cancer treatment viewed on 25 January2006. www.cancervax. com/info/index.htm.Apaja, M. (1980), “Evaluation of toxicity and carcinogenity of malonaldehyde”, An experimental study inSwiss mice, Thesis Acta Univ Ouluensis Ser D, 55.Bagalkotkar, G. et al. (2006), "Phytochemicals from Phyllanthus niruri Linn. and their pharmacological 22
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  • 10. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.1, No.4, 2011 Figure-1 Effect of PNE on reduced glutathione (GSH) content in liver and skin of mice. * (p ≤ 0.001) Figure-2 Effect of PNE on lipid peroxidation (LPO) level in liver and skin tissue of mice. * (p ≤ 0.001)Figure-3 Effect of PNE on the activity of superoxide dismutase (SOD) in liver and skin tissue of mice. * (p ≤ 0.001) 25
  • 11. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.1, No.4, 2011 Figure-4 Effect of PNE on the activity of catalase (CAT) in liver and skin tissue of mice. * (p ≤ 0.001) Figure-5 Effect of PNE on vitamin C content in liver and skin tissue of mice. * (p ≤ 0.001) Figure- 6 Effect of PNE on total proteins content in liver and skin tissue of mice. * (p ≤ 0.001) 26
  • 12. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.1, No.4, 2011 HK E EH B D D.I. S (A) (B) EH K HK S (C) (D) K (E) Figure- 7 Photomicrograph showing histological sections of skin and tumors of mice of different groups. (A) Group -I skin, (B) Group- III skin, (C) Group- IV skin, (D) Group-III tumor, (E) Group-IV tumor E- epidermis, D- dermis, B- basal Lamina, HK- hyperkyratosis, E.H- epidermal hyperplasia, D.I.- dermal invasion, S- sebaceous gland, K- keratin pearl Table 1. Protective effect of P.niruri on DMBA induced carcinogenesis in mice Treatment groups Body weight (g) Tumor size Tumor Average latent Mean ± SE (mm) weight period (gm) (Weeks) Initial Final 2-5 6-9Gr. I Vehicle treated control 25.52±1.72 33.20±1.24 - - - -Gr. II PNE treated control 26.46±2.18 32.98±1.56 - - - -Gr. III Carcinogen control 25.60±1.64 30.81±2.29 44 18 1.37 7.93Gr. IV PNE experimental 25.72±1.58 33.06±1.30 11 4 0.38 10.66 27
  • 13. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.1, No.4, 2011 Table 2. Protective effect of P.niruri on DMBA induced carcinogenesis in mice Treatment groups Cummulative Tumor Tumor yield Tumor burden number of incidence (average number (tumors/tumor Papillomas (%) of tumors/mouse) bearing mouse)Gr. I Vehicle treated control - - - -Gr. II PNE treated control - - - -Gr. III Carcinogen control 62 100 6.2 6.2Gr. IV PNE experimental 15 40 1.5 3.75 28